Imaging device analysis systems and imaging device analysis methods

ABSTRACT

Imaging device analysis systems and imaging device analysis methods are described. According to one embodiment, an imaging device analysis system includes a light source configured to output light for use in analyzing at least one imaging component of an imaging device, wherein the imaging device is configured to generate images responsive to received light, and processing circuitry coupled with the light source and configured to control the light source to optically communicate the light to the imaging device, wherein the processing circuitry is further configured to access image data generated by the imaging device responsive to the reception, by the imaging device, of the light from the light source and to process the image data to analyze an operational status of the at least one imaging component.

RELATED PATENT DATA

This application resulted from a continuation in part of and claimspriority to U.S. patent application Ser. No. 10/818,622, filed on Apr.5, 2004, entitled “Imaging Device Calibration Methods, Imaging DeviceCalibration Instruments, Imaging Devices, And Articles Of Manufacture”,listing Jeffrey M. DiCarlo as inventor, and the disclosure of which isincorporated by reference herein.

FIELD OF THE DISCLOSURE

Aspects of the disclosure relate to imaging device analysis systems andimaging device analysis methods.

BACKGROUND OF THE DISCLOSURE

Imaging systems of various designs have been used extensively forgenerating images. Exemplary imaging systems include copiers, scanners,cameras, and more recently digital cameras, and other devices capable ofgenerating images. Color imaging systems have also experiencedsignificant improvements and are increasing in popularity. Color imagingsystems may be calibrated to increase accuracy of various imageprocessing algorithms (e.g., illuminant estimation, color correction,etc.), and also to increase the color accuracy of final reproductions.

For example, even identically configured imaging systems may vary fromone another due to product tolerances or design variances. Referring toFIG. 1, a graphical representation of relative responsivity versuswavelength is shown for two hundred digital cameras corresponding to thesame product. FIG. 1 illustrates the variations in blue, green, and redsensor responsivities of the sampled cameras represented by respectivebands 4, 6 and 8. The illustrated bands have widths illustrating thesize of the variations between respective cameras although the camerasstructurally comprise the same components.

One color calibration technique uses reflective charts. Reflectivecharts can be utilized to calibrate a camera quickly and they arerelatively inexpensive. However, calibrations implemented usingreflective charts may not be accurate enough for utilization withcameras. Monochromators, on the other hand, can produce very accuratecalibrations of color imaging systems including cameras. However, thecalibration procedure with monochromators may take a relatively longperiod of time to complete, the devices are expensive, and an accurateand controlled light source is typically used.

Other conventional arrangements for analyzing imaging devices haveassociated drawbacks. For example, one device for shutter testing of animaging device (e.g., a Camlogix SH-T2) utilizes incandescent lamps anda time calibrated sensor placed in a film plane of a film camera whichis less practical for testing of digital cameras. Further, usage ofincandescent lamps presents issues with respect to controlling theduration of illumination as well as color and luminance of emittedlight. Scanners have been calibrated using white cards which does notpermit color calibration in color implementations. Other devices fortesting lenses and color (e.g., K-Series TV Optoliner available fromDavidson Electronics) utilize a test pattern which is projected onto asensor plane. These systems have drawbacks of careful set-up and beingdesigned for analyzing television cameras. In addition, typicalconventional analysis systems use different pieces of equipment forperforming different tests or analysis.

At least some aspects of the disclosure are related to improved imagingdevice analysis devices, systems and methods.

SUMMARY

According to some aspects, exemplary imaging device analysis systems andimaging device analysis methods are described.

According to one embodiment, an imaging device analysis system comprisesa light source configured to output light for use in analyzing at leastone imaging component of an imaging device, wherein the imaging deviceis configured to generate images responsive to received light, andprocessing circuitry coupled with the light source and configured tocontrol the light source to optically communicate the light to theimaging device, wherein the processing circuitry is further configuredto access image data generated by the imaging device responsive to thereception, by the imaging device, of the light from the light source andto process the image data to analyze an operational status of the atleast one imaging component.

According to another embodiment, an imaging device analysis methodcomprises outputting infrared light for communication to an imagingdevice configured to generate images responsive to received light,wherein the imaging device is configured to filter infrared light,accessing image data generated by the imaging device responsive to thelight communicated to the imaging device, processing the image data todetermine operability of infrared filtering of the imaging device, andindicating the operability of the infrared filtering responsive to theprocessing.

Other embodiments are described as is apparent from the followingdiscussion.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of responsivity of a sampling ofimaging systems.

FIG. 2 is an illustrative representation of an exemplary calibrationinstrument and imaging device according to an illustrative embodiment.

FIG. 3 is a functional block diagram of circuitry of a calibrationinstrument according to one embodiment.

FIG. 4 is a functional block diagram of circuitry of an imaging deviceaccording to one embodiment.

FIG. 5 is an illustrative representation of an optical interface of acalibration instrument according to one embodiment.

FIG. 6 is a graphical representation of radiance versus wavelength forlight emitted from the optical interface according to one embodiment.

FIG. 7 is a flow chart representing an exemplary imaging devicecalibration method according to one embodiment.

FIG. 8 a is a flow chart representing exemplary data acquisitionaccording to one embodiment.

FIG. 8 b is a flow chart representing exemplary data acquisitionaccording to another embodiment.

FIG. 9 is a flow chart representing exemplary data processing accordingto one embodiment.

FIG. 10 is a graphical representation comparing exemplary calibrationtechniques.

FIG. 11 is a graphical representation comparing estimated and measuredrelative responsivities using a Macbeth chart calibration technique.

FIG. 12 is a graphical representation comparing estimated and measuredrelative responsivities using a MacbethDC chart calibration technique.

FIG. 13 is a graphical representation comparing estimated and measuredrelative responsivities using an emissive calibration instrumentaccording to one embodiment.

FIG. 14 is an illustrative representation of an imaging system accordingto one embodiment.

FIG. 15 is an illustrative representation of a light source according toone embodiment.

FIGS. 16A-16B are graphical representations of light received by animage sensor of an imaging device according to one embodiment.

FIG. 17 is a flow chart of an exemplary method for analyzing infraredfiltering operations of an imaging device according to one embodiment.

FIG. 18 is an illustrative representation of a light source according toone embodiment.

FIG. 19 is an illustrative representation of a mask according to oneembodiment.

FIG. 20 is a flow chart of an exemplary method for analyzing optics ofan imaging device according to one embodiment.

FIGS. 21A-21B are illustrative representations of light received by animage sensor according to one embodiment.

FIGS. 22A-22B are graphical representations of light received by animage sensor according to one embodiment.

FIG. 23 is an illustrative representation of a light source according toone embodiment.

FIG. 24 is an illustrative representation of a mask according to oneembodiment.

FIGS. 25A-25B are graphical representations of light received by animage sensor according to one embodiment.

FIG. 26 is a flow chart of an exemplary method for analyzing optics ofan imaging device according to one embodiment.

FIGS. 27A-27B are illustrative representations of light received by animage sensor and indicative of pin cushion distortion and barreldistortion, respectively, according to one embodiment.

FIG. 28 is a flow chart of an exemplary method for analyzing optics ofan imaging device according to one embodiment.

FIG. 29 is an illustrative representation of a light source according toone embodiment.

FIG. 30 is an illustrative representation of light received by an imagesensor according to one embodiment.

FIG. 31 is a flow chart of an exemplary method for analyzing exposurespeed of an imaging device according to one embodiment.

FIG. 32 is a flow chart of an exemplary method for determiningcorrection factors for an imaging device according to one embodiment.

DETAILED DESCRIPTION

At least some aspects of the disclosure provide apparatus and methodswhich enable fast and accurate calibration of an imaging device. In oneembodiment, optical characteristics such as a responsivity functionand/or a transduction function of an imaging device may be measured todetermine how the associated imaging device responds to input lightsignals. The determined optical characteristics may be utilized tocalibrate the respective imaging device. According to exemplaryimplementations, emissive light sources as opposed to reflectivearrangements are used to determine the optical characteristics and whichenable real time fast and relatively inexpensive calibration of animaging device (e.g., on an assembly line).

Referring to FIG. 2, an imaging system 10 according to one embodiment isshown. The depicted imaging system 10 includes an exemplary imagingdevice calibration instrument 12 and an imaging device 14. Instrument 12may be referred to as an emissive calibration instrument in at least oneembodiment wherein one or more light source of the instrument 12 emitslight which is used for implementing determination of calibration dataand calibration of a device 14.

In at least one embodiment, calibration instrument 12 is used to providecalibration data which may be utilized to calibrate imaging device 14.In at least some embodiments described herein, calibration instrument 12may operate in conjunction with imaging device 14 to provide thecalibration data. Calibration data includes optical characteristics suchas responsivity and/or transduction functions of the respective imagingdevice 14 in exemplary embodiments. The calibration data may be utilizedto calibrate the individual respective device 14 used to obtain thecalibration data. For example, image processing algorithms of imagingdevice 14 may be tailored to improve imaging operations thereofincluding the ability of imaging device 14 to produce pleasing and/orfaithful images of captured scenes.

Imaging device 14 comprises a color digital camera in the illustratedsystem. Other configurations of imaging device 14 configured to generateimage data responsive to received images are possible (e.g., scanner,color copier, color multiple function peripheral, etc.).

Referring again to calibration instrument 12, the depicted exemplaryembodiment includes a light source 20, a light randomizer 22, and anoptical diffuser 24. For ease of discussion, exemplary components 20,22, 24 are shown in exploded view. In typical implementations ofcalibration instrument 12, components 20, 22, 24 are sealed with respectto one another to prevent the introduction of ambient light intoinstrument 12. Processing circuitry of calibration instrument 12 mayalso be provided to control calibration operations as is discussed belowwith respect to the exemplary circuitry of FIG. 3.

Light source 20 may be embodied in different configurations in differentembodiments of calibration instrument 12. Further, light source 20 maybe controlled in different embodiments to emit different lightsimultaneously and/or sequentially. Different light comprises lighthaving different emission characteristics, such as differentwavelengths, intensities or spectral power distributions.

For example, the depicted configuration of light source 20 comprises aplurality of regions 26 which are individually configured to emit lighthaving different wavelengths and/or intensities compared with otherregions 26. Accordingly, the light of at least some of regions 26 may beboth spatially and spectrally separated from light of other regions 26in the embodiment of calibration instrument 12 in FIG. 2. In someembodiments, the light having different wavelengths and/or intensitiesmay be emitted simultaneously. In other embodiments, some of which aredescribed below, light having different wavelengths and/or intensitiesmay be emitted sequentially.

Individual ones of the regions 26 may comprise one or more lightemitting device (not shown). Exemplary light emitting devices includenarrow-band devices which provide increased accuracy compared withbroad-band reflective patches. Light emitting devices of regions 26include light emitting diodes (LEDs) and lasers in exemplaryembodiments. Other configurations of light emitting devices of regions26 may be utilized. In one example, individual regions 26 comprise a 3×3square of light emitting devices configured to emit light of the samewavelength and intensity.

In the depicted exemplary embodiment, light randomizer 22 comprises aplurality of hollow tubes corresponding to respective ones of regions 26of light source 20. Light randomizer 22 is configured to presentsubstantially uniform light for individual ones of regions 26 todiffuser 24 in the described configuration. Internal surfaces of thetubes of light randomizer may have a relatively bright white mattesurface. Other configurations of light randomizer 22 are possible. Forexample, light randomizer 22 may comprise a single hollow tube in atleast one other embodiment of instrument 12 having a single lightemitting region described below.

Optical diffuser 24 comprises an optical interface 27 configured topresent substantially uniform light for individual ones of regions 26(and respective regions 28 of optical interface 27 discussed below) toimaging device 14 for use in calibration operations. Otherconfigurations of optical interface 27 apart from the illustratedoptical diffuser 24 may be utilized to output light to imaging device14. An exemplary optical diffuser 24 comprises a translucent acrylicmember. The illustrated exemplary optical diffuser 24 is configured tooutput light corresponding to light emitted by light source 20. Forexample, the exemplary depicted optical interface 27 comprises aplurality of regions 28 corresponding to respective regions 26 of lightsource 20. In other embodiments, more or less regions 28 may be providedcorresponding to the provided number of regions 26 of light source 20.In at least one embodiment, optical randomizer 22 and diffuser 24provide different light corresponding to respective ones of regions 28and for individual ones of the regions 28, the respective light issubstantially uniform throughout the area of the respective region 28.In other possible implementations, another optical diffuser may beimplemented intermediate light source 20 and light randomizer 22 orwithin light randomizer 22.

In one embodiment, light randomizer 22 comprises plural aluminumsubstantially square tubes corresponding to regions 26 of light source20. The tubes may individually have a length of 2.5 inches betweensource 20 and interface 27 and square dimensions of 1 inch by 1 inch.The interior surfaces of the tubes may be coated with a white coatingsuch as OP.DI.MA material having part number ODMO1-FO1 available fromGigahertz-Optik. Diffuser 24 may comprise a plurality of pieces of whitetranslucent acrylic material having part number 020-4 available fromCyro Industries with dimensions of 1 inch by 1 inch comprisingindividual ones of regions 28 and individually having a thickness of ⅛inch. Other configurations or embodiments are possible.

Referring to FIG. 3, exemplary circuitry 30 of calibration instrument 12is shown. The depicted circuitry 30 includes a communications interface32, processing circuitry 34, storage circuitry 36, light source 20 and alight sensor 38. More, less or alternative circuit components may beprovided in other embodiments.

Communications interface 32 is configured to establish communications ofcalibration instrument 12 with respect to external devices. Exemplaryconfigurations of communications interface 32 include a USB port, serialor parallel connection, IR interface, wireless interface, or any otherarrangement capable of uni or bidirectional communications. Anyappropriate data may be communicated using communications interface 32.For example, as described below, communications interface 32 may beutilized to communicate one or more emission characteristic of lightsource 20 and/or one or more determined optical characteristics of therespective imaging device 14 to be calibrated.

In one embodiment, processing circuitry 34 may comprise circuitryconfigured to implement desired programming. For example, processingcircuitry 34 may be implemented as a processor or other structureconfigured to execute executable instructions including, for example,software and/or firmware instructions. Other exemplary embodiments ofprocessing circuitry include hardware logic, PGA, FPGA, ASIC, statemachines, and/or other structures. These examples of processingcircuitry 34 are for illustration and other configurations are possible.

Processing circuitry 34 may be utilized to control operations ofcalibration instrument 12. In one embodiment, processing circuitry 34 isconfigured to automatically control the timing of emission of light fromthe instrument 12 (e.g., control the timing to simultaneously and/orsequentially emit light having different wavelengths and/or intensitiesfrom instrument 12). In one embodiment, processing circuitry 34 mayautomatically control the timing and the emission of the light withoutuser intervention.

Storage circuitry 36 is configured to store electronic data and/orprogramming such as executable instructions (e.g., software and/orfirmware), calibration data, or other digital information and mayinclude processor-usable media. In addition to the calibration datadescribed above, additional exemplary calibration data may include oneor more emission characteristics of light emitted using opticalinterface 27 of calibration instrument 12. As discussed below, exemplaryemission characteristics include spectral power distributions (SPDs) oflight emitted at optical interface 27 according to one embodiment.Spectral power distributions include emission characteristics includingwavelengths of the emitted light and associated intensities of the lightfor the respective wavelengths of light.

Processor-usable media includes any article of manufacture which cancontain, store, or maintain programming, data and/or digital informationfor use by or in connection with an instruction execution systemincluding processing circuitry in the exemplary embodiment. For example,exemplary processor-usable media may include any one of physical mediasuch as electronic, magnetic, optical, electromagnetic, infrared orsemiconductor media. Some more specific examples of processor-usablemedia include, but are not limited to, a portable magnetic computerdiskette, such as a floppy diskette, zip disk, hard drive, random accessmemory, read only memory, flash memory, cache memory, and/or otherconfigurations capable of storing programming, data, or other digitalinformation.

Light source 20 may be configured in exemplary arrangements as describedabove. For example, light source 20 may be configured to emit light ofdifferent wavelengths and/or intensities in one embodiment. Thedifferent wavelengths and/or intensities may be defined by a pluralityof regions 26 as described above. In another embodiment, light source 20is configured to emit light of a substantially constant wavelengthand/or intensity and a plurality of spatially separated filterspositioned downstream of light source 20 and corresponding to regions 26may be utilized to provide light of any different desired wavelengthsand/or intensities. In another embodiment described below, light source20 may be configured to sequentially emit different light using a singleregion. Other arrangements are possible.

Light sensor 38 is optically coupled with light source 20 and isconfigured to receive emitted light therefrom. In one example, lightsensor 38 is implemented as a photodiode although other configurationsare possible. One or more light sensor 38 may be positioned within lightrandomizer 24 in some embodiments (e.g., one light sensor 38 may bepositioned in light randomizer 22 implemented as a single hollow tube inone exemplary configuration described herein). In other arrangementshaving plural regions 26, light sensor 38 may be optically coupled viaan appropriate light pipe (not shown) or other configuration with theregions 26 and corresponding to emitted light having differentwavelengths and/or intensities.

Light sensor 38 is configured to monitor emitted light for calibrationpurposes of calibration instrument 12 in one arrangement. For example,at least some configurations of light source 20 may provide light whichdrifts in wavelength and/or intensity over time. Light sensor 38 may beutilized to monitor the light and indicate to a user that instrument 12is out of calibration and service is desired. For example, calibrationinstrument 12 may be considered to be out of calibration if intensitiesof different wavelengths of light vary with respect to one another.Exemplary recalibration of calibration instrument 12 may includere-determining the emission characteristics (e.g., spectral powerdistributions) of light emitted from the optical interface 27.

Referring to FIG. 4, imaging device 14 is illustrated in an exemplaryconfiguration as a digital camera. As mentioned previously, imagingdevice 14 may be embodied in other configurations to generate imagesfrom scenes or received light. Imaging device in the illustratedconfiguration includes processing circuitry 40, storage circuitry 42, astrobe 44, an image sensor 46, a filter 48, optics 50, and acommunications interface 52.

In one embodiment, processing circuitry 40 may be embodied similar toprocessing circuitry 34 described above and comprise circuitryconfigured to implement desired programming. Other exemplary embodimentsof processing circuitry include different and/or alternative hardware tocontrol operations of imaging device 14 (e.g., control strobe 44, optics50, data acquisition and storage, processing of image data,communications with external devices, and any other desired operations).These examples of processing circuitry 40 are for illustration and otherconfigurations are possible.

Storage circuitry 42 is configured to store electronic data (e.g., imagedata) and/or programming such as executable instructions (e.g., softwareand/or firmware), or other digital information and may includeprocessor-usable media similar to the above-described storage circuitry36 in at least one embodiment.

Strobe 44 comprises a light source configured to provide light for usagein imaging operations. Processing circuitry 40 controls operation ofstrobe 44 in the described embodiment. Strobe 44 may be disabled,utilized alone or in conjunction with other external sources of light(not shown).

Image sensor 46 is configured to provide raw image data of a pluralityof raw images. The raw image data comprises digital data correspondingto a plurality of pixels of the raw images formed by image sensor 46.For example, the raw images comprise bytes corresponding to the colorsof red, green and blue at respective pixels in an exemplary RGBapplication. Other embodiments may utilize or provide other colorinformation. Image sensor 46 may comprise a plurality of photosensitiveelements, such as photodiodes, corresponding to the pixels andconfigured to provide the raw digital data usable for generating images.For example, image sensor 46 may comprise a raster of photosensitiveelements (also referred to as pixel elements) arranged in 1600 columnsby 1280 rows in one possible configuration. Other raster configurationsare possible. Photosensitive elements may individually comprise chargecoupled devices (CCDs) or CMOS devices in exemplary configurations. Inone specific example, image sensor 46 may utilize X3 technology insensor arrangements available from Foveon, Inc.

Filter 48 is provided upstream of image sensor 46 to implement anydesired filtering of light received by imaging device 14 prior tosensing by image sensor 46. For example, in one embodiment, filter 48may remove infrared light received by imaging device 14.

Optics 50 includes appropriate lens and an aperture configured to focusand direct received light for creation of images using image sensor 46.Appropriate motors (not shown) may be controlled by processing circuitry40 to implement desired manipulation of optics 50 in one embodiment.

Communications interface 52 is configured to establish communications ofimaging device 14 with respect to external devices (e.g., calibrationinstrument 12). Exemplary configurations of communications interface 52include a USB port, serial or parallel connection, IR interface,wireless interface, or any other arrangement capable of uni orbidirectional communications. Communications interface 52 may beconfigured to couple with and exchange any appropriate data withcommunications interface 32 of calibration instrument 12 or otherexternal device. For example, communications interface 52 may beutilized to receive one or more emission characteristic of light source20 and/or one or more determined optical characteristic of therespective imaging device 14. Further, interface 52 may output sensordata generated by image sensor 46 and which may be used to implementimage processing operations including determination of opticalcharacteristics of imaging device 14 as described below.

Referring to FIG. 5, an exemplary configuration of optical interface 27is shown. The depicted optical interface 27 corresponds to theembodiment of calibration instrument 12 shown in FIG. 2 and includes aplurality of regions 28 of different light having different wavelengthsand/or intensities.

In the illustrated configuration, optical interface 27 includes pluralrows 60 of colored regions and a single row 62 of white regions. More,less or regions of other wavelengths and/or intensities may be providedin other embodiments of optical interface 27.

Colored region rows 60 provide plural regions 28 of light havingdifferent wavelengths. For example, in the depicted embodiment, rows 60include regions 28 sequentially increasing in wavelength at incrementsof 25 nm from ultraviolet light (375 nm) to infrared light (725 nm)providing light which is spectrally and spatially separated. In theillustrated example, row 62 comprises a plurality of regions W1-W5 ofthe same relative spectral power distribution and which increase inintensity. The relative intensity of the white patches may be 0.01,0.03, 0.10, 0.30, and 1 for respective ones of regions W1-W5.

According to the exemplary embodiment of FIG. 5, the number of lightemitting devices and/or the drive currents for the light emittingdevices may be varied between respective regions 28 to provide thedesired spectral power distributions of emitted light. Otherconfigurations are possible in other embodiments.

In one embodiment, the regions 28 of FIG. 5 may be numbered 1 to 15sequentially from left to right for each of the rows starting with thetop row and continuing to the bottom row. Exemplary light emittingdevices may comprise LEDs available from Roither Lasertechnik and havethe following part numbers for the respective regions 28: (1) 380D30,(5) HUBG-5102L, (13) ELD-670-534, (14) ELD-700-534, and (15)ELD-720-534. Remaining exemplary light emitting devices may compriseLEDs available from American Opto and have the following part numbersfor the respective regions 28: (2) L513SUV, (3) L513SBC-430NM, (4)L513NBC, (6) L513NBGC, (7) L513NPGC, (8) L513UGC, (9) L513NYC-E, (10)L513UOC, (11) L513NEC, (12) L513TURC, and (W1-W5) L513NWC.

In this example, the drive currents may be constant for the lightemitting devices of all of the regions 28 for rows 60 (e.g., 18-20 mA)and the number of light emitting devices per region 28 are variedaccording to: (1) 4, (2) 1, (3) 14, (4) 2, (5) 4, (6) 3, (7) 1, (8) 27,(9) 3, (10) 2, (11) 1, (12) 2, (13) 2, (14) 2, and (15) 1. The number oflight emitting devices for individual ones of the regions 28 of row 62may be the same (e.g., four) and the following exemplary drive currentsmay be used: 0.2, 0.6, 2, 6 and 20 mA for respective ones W1-W5 ofregion 28. The above example is for illustration and otherconfigurations or variations are possible.

As described further below, utilization of optical interface 27 shown inFIG. 5 including regions 28 of varying wavelength and/or intensityenables simultaneous determination of responsivity and transductionfunctions of imaging device 14, for example, via a single exposure ofthe device 14 to light emitted from optical interface 27 using imagingdevice 14. Other configurations of optical interface 27 are possible asdiscussed herein (e.g., providing an optical interface wherein onlywavelength or intensity are varied between regions 26, providing anoptical interface with only a single emission region for sequentiallyemitting light of the same wavelength and/or intensity, etc.).

Provision of light of different wavelengths by calibration instrument 12may be utilized to determine a responsivity function of imaging device14. In the embodiment of optical interface 27 illustrated in FIG. 5,plural regions 26 of rows 60 may simultaneously emit light fordetermination of the responsivity function via a single exposure theretoby imaging device 14 due to the spatially and spectrally separatedregions 26 of rows 60.

Referring to FIG. 6, the emission of light via optical interface 27(i.e., and received by imaging device 14) may be optimized to facilitatedetermination of the responsivity function of the imaging device 14being calibrated. The graphical representation of FIG. 6 illustratesspectral power distributions of light emitted by light source 20 andprovided at regions 28 of optical interface 27 which facilitate theresponsivity analysis of imaging device 14. The spectral powerdistributions include exemplary radiance values for the regions 28 ofoptical interface 27 depicted in FIG. 5 increasing in wavelength fromleft to right along the x-axis.

As mentioned above, the number of light emitting devices of source 20may be varied for individual regions 26 to provide differentintensities. In another embodiment, the number of light emitting devicesmay be the same for individual regions 26 and the drive currents of thelight emitting devices of the respective regions 26 may be varied toprovide desired intensities. Other arrangements may be used to providedesired spectral power distributions. In one embodiment, the intensitiesmay be selected to approximate the exemplary spectral powerdistributions depicted in FIG. 6 during calibration of instrument 12itself. Once the appropriate drive currents of the light emittingdevices of respective regions 26 (or other configuration parameters) aredetermined, instrument 12 may be calibrated to drive the light emittingdevices using the determined drive currents or parameters. In oneembodiment, the light emitting devices of a respective region 26 may bedriven using the same drive current while drive currents used to drivelight emission devices of different regions 26 may be different. Otherconfigurations apart from varying the number of light emitting devicesand/or drive currents for respective regions 26 may be used in otherembodiments as mentioned above.

Further, the spectral power distribution of light emitted at opticalinterface 27 using the drive currents may be determined followingcalibration of instrument 12. In one example, the spectral powerdistribution of light emitted at optical interface 27 may be measuredusing a spectral radiometer. The measured spectral power distribution ofcalibration instrument 12 may be stored as an emission characteristic ofcalibration instrument 12 using storage circuitry 36 or otherappropriate circuitry and subsequently utilized during calibrationoperations of one or more imaging device 14. New drive currents and/orspectral power distributions may be determined during recalibration ofinstrument 12.

Emission characteristics may also be provided and stored for individualregions 28 of row 62. As mentioned previously, at least some of theregions 28 may be configured to vary intensity of light for a givenwavelength of light (e.g., the regions of row 62). Data regarding theintensities of light corresponding to regions 28 may be stored as anemission characteristic for subsequent usage in calibration of one ormore imaging device 14. The intensity data may also be extracted fromthe spectral power distributions of light from regions 28 within row 62.

Referring to FIG. 7, an exemplary method for implementing calibration ofan imaging device 14 using calibration instrument 12 is shown. Othermethods are possible including more, less or alternative steps.

At a step S1, an embodiment of calibration instrument 12 having a lightsource is provided along with at least one emission characteristic oflight emitted from the light source.

At a step S2, the imaging device 14 to be calibrated is aligned withcalibration instrument 12.

At a step S3, image sensor 46 of imaging device 14 is exposed to lightemitted from the light source.

At a step S4, image sensor 46 senses the light and generates sensor datawhich is indicative of the sensing by the image sensor 46.

At a step S5, appropriate processing circuitry determines an opticalcharacteristic of imaging device 14 using the emission characteristicand the sensor data. The optical characteristic may be utilized tocalibrate imaging device 14. The exemplary method of FIG. 7 may berepeated for other imaging devices 14.

Referring to FIG. 8 a, a flow chart illustrates an exemplary method fordata acquisition during calibration of an associated imaging device 14using the calibration instrument 12 described with reference to FIG. 2.

At a step S10, the imaging device to be calibrated is brought intoalignment to receive light emitted from the optical interface of thecalibration instrument 12. Once aligned, the light source 20 ofcalibration instrument 12 is controlled to emit light at regions 28 ofoptical interface 27. Imaging device 14 is configured to provide theoptical interface 27 into focus and to expose the image sensor 46 tolight from calibration instrument 12 (e.g., takes a photograph) toreceive the light emitted from optical interface 27.

At a step S12, sensor data is generated by image sensor 46 responsive tothe exposing in step S10. In one embodiment, individual pixels of imagesensor 46 are configured to provide sensor data comprising RGB values.Pixel locations of image sensor 46 may correspond to regions 28 ofoptical interface 27. Accordingly, a plurality of pixels of image sensor46 may be identified which correspond to individual ones of regions 28.RGB values from individual ones of the pixels which correspond torespective individual regions 28 and may be averaged using processingcircuitry 34, 40 or other desired circuitry in one embodiment to providea single averaged RGB value for each of regions 28. According to oneembodiment, the sensor data comprising averaged RGB values may beutilized for calibration of imaging device 14 as described below.

Data acquisition operations are described below with respect to anotherembodiment of calibration instrument 12. Calibration instrument 12according to the other presently described embodiment includes anoptical interface having a single region (not shown) to output light forcalibration of imaging device 14. For example, as opposed to arranginglight emitting devices of different wavelengths and/or intensitiesaccording to regions 26 as described above, light emitting devices ofthe light source having different wavelengths or intensities may bedistributed around an entirety of the area of the region of the opticalinterface.

In one embodiment, it is desired for the light emitting devices of thelight source to provide a substantially uniform distribution of lightacross an entirety of the area of the region of the optical interface.In one possible implementation, individual ones of the light emittingdevices comprising twenty different wavelengths or intensities may bepositioned adjacent to one another in sequence in both rows and columnsto provide a substantially uniform emission of light across the regionof the optical interface for individual ones of the wavelengths onintensities. Other patterns of distribution of the light emittingdevices are possible.

In one operational embodiment, only the light emitting devices of acommon wavelength or intensity may be controlled to emit light at anygiven moment in time. According to this embodiment, the light emittingdevices of a first wavelength of light may be controlled to emitrespective light substantially uniform across the area of the region.Thereafter, the light emitting devices for the remaining wavelengths maybe sequentially individually controlled to emit light of the respectivewavelengths in sequence providing temporal and spectral separation ofthe emitted light. If present, light emitting devices having differentintensities for a given wavelength may thereafter be individuallyconfigured to emit light in sequence to enable transduction calibrationoperations described further below. Accordingly, in one embodiment, thelight emitting devices of respective wavelengths or intensities may besequentially configured to emit respective light. More specifically,light emitting devices having a common wavelength may be sequentiallycontrolled to individually emit light starting at 375 nm and progressingto 725 nm and followed by the emission of light from light emittingdevices configured to provide light of a common wavelength and variedintensity from W1 to W5. Imaging device 14 may sense emitted light foreach of the respective emitted wavelengths 375 nm-725 nm and intensitiesW1-W5 of light in one embodiment. Sensor data is then provided byimaging device 14 for each of the wavelengths and intensities of light.

Referring to FIG. 8 b, exemplary data acquisition operations accordingto the second above-described embodiment having an optical interface 27with a single region providing sequentially emitted different light aredescribed.

At a step S20, the calibration instrument is controlled to emit lighthaving a single wavelength. The image sensor of the imaging device to becalibrated is exposed to the emitted light.

At a step S22, an average RGB value for the respective wavelength may bedetermined from pixel sensor data of the image sensor using processingcircuitry 34, 40 or other desired circuitry.

Thereafter, the processing may return to step S20 whereupon theinstrument controls the emission of light of the next wavelengthenabling generation of sensor data for the respective wavelength usingthe imaging device 14. The process of FIG. 8 b may be repeated toprovide sensor data comprising averaged RGB values in the describedembodiment for as many different wavelengths or intensities of lightemitted using the calibration instrument.

The above-described embodiments are provided to illustrate exemplarydata acquisition techniques for implementing imaging device calibrationoperations. Other data acquisition methods and/or apparatus may be usedin the other embodiments.

Referring to FIG. 9, the acquired data is processed followingacquisition to determine calibration data of the imaging device 14.Exemplary processing includes determining calibration data comprisingoptical characteristics (e.g., responsivity and/or transductionfunctions) for the respective imaging device 14 according to oneembodiment. As mentioned above, processing circuitry 34, 40 and/or otherappropriate processing circuitry may perform data acquisitionoperations. Similarly, processing circuitry 34, 40 and/or otherappropriate processing circuitry may be utilized to process the acquireddata for example as shown in FIG. 9. Further, data acquisition andprocessing may be performed by the same or different processingcircuitry.

In the illustrated exemplary processing of FIG. 9, opticalcharacteristics including responsivity and transduction functions of theimaging device 14 are determined. In other embodiments, only one ofresponsivity or transduction functions, and/or alternativecharacteristics of the imaging device 14 are determined. Further,additional optical characteristics or other information for use incalibration of imaging device 14 may be determined. For example,responsivity and/or transduction functions may be further processed byappropriate processing circuitry 34, 40 or other processing circuitry(not shown). For example, a color correction matrix, an illuminantestimation matrix and/or other information may be derived from theresponsivity and transduction functions.

Steps S30-S34 illustrate exemplary processing for determining aresponsivity function of imaging device 14.

Steps S40-S44 illustrate exemplary processing for determining atransduction function of imaging device 14. Other processing may beutilized according to other arrangements (not shown).

At step S30, the sensor data obtained from image sensor 46 including theaveraged RGB values described above for the respective individualregions 28 of rows 60 in the described embodiment may define a matrix r.

At step S32, the emission characteristic comprising spectral powerdistributions (SPDs) of the regions 28 in the described embodiment maydefine a matrix S.

At step S34, the responsivity function R may be determined usingmatrices r, S and the equation R=pinv(S^(T))r^(T) in the describedexample.

The transduction function may be determined in parallel with thedetermination of the responsivity function in the illustrated example.

Referring to step S40, the sensor data from image sensor 46 includingthe averaged RGB values for the respective individual regions 28 of row62 in the described embodiment may define a matrix r_(w).

At step S42, the emission characteristic comprising spectral powerdistributions of the regions 28 in the described embodiment may define amatrix S_(w).

At step S44, the transduction function g(x)−>g(1^(T)S_(w))=r_(w) may besolved using matrices r_(w), S_(w) in the described example.

The above-described methods of FIG. 9 may be used to determine one ormore optical characteristic for respective individual ones of theimaging devices 14 which provided the respective sensor data indicativeof the circuitry of the respective imaging devices 14, and accordingly,the above-described processes may be performed for individual ones ofimaging devices 14 to be calibrated to determine the respectiveappropriate one or more optical characteristic for the respectivedevices 14. The above-described methods of FIG. 9 are exemplary andother processing or methods may be utilized to determine responsivityand/or transduction functions or other optical characteristics ofimaging device 14 in other embodiments.

Once determined, the optical characteristics may be used to calibratethe respective imaging devices 14. For example, optical characteristicscomprising responsivity and transductance functions may be used toincrease the accuracy of image processing algorithms (e.g., illuminantestimation and color correction) of respective imaging devices 14, andalso to increase the color accuracy of final reproductions.

As described herein in one embodiment, the exemplary apparatus and/ormethods may be used to determine whether components of imaging device 14are defective (e.g., sensor 46, filter 48, etc.). For example, theability of the respective imaging devices 14 to remove infrared or otherlight may also be monitored using calibration instruments 12 discussedabove and configured to emit infrared or other light. For example, afilter of imaging device 14 and configured to remove certain light(e.g., infrared) may be identified as defective if the sensor datagenerated by the respective imaging device 14 responsive to lightemitted from optical interface 27 of calibration instrument 12 (andincluding infrared or other desired light) indicates that the receivedlight included emitted infrared or the other light which was not removedby filter 48.

In one embodiment, the determined optical characteristics may becommunicated to respective imaging devices 14 which implementappropriate calibration if the optical characteristics were determinedusing processing circuitry 34 of calibration instrument 12 (or otherprocessing circuitry external of imaging devices 14). Alternately,processing circuitry 40 of imaging devices 14 may determine the opticalcharacteristics of the respective devices 14. In another embodiment, thecalibration may be performed externally of imaging devices 14 using thedetermined optical characteristics and the calibrated image processingalgorithms may be subsequently provided to the respective imagingdevices 14. In yet another embodiment, processing circuitry 40 ofimaging devices 14 may be configured to utilize the determined (e.g.,internally or externally) optical characteristics to implement thecalibration internally of the imaging devices 14. In sum, anyappropriate processing circuitry may be configured to generate one ormore optical characteristic for the respective imaging devices 14 andthe same or other processing circuitry may utilize the one or moreoptical characteristic to implement the calibration.

Referring to FIG. 10, a graphical representation is shown of singularvalue decomposition of different calibration methods including exemplaryemissive aspects described herein compared with usage of reflectivepatches (Macbeth and MacbethDC) and a monochromator.

The relatively high and constant singular value decomposition using theexemplary emissive calibration instrument 12 of FIG. 2 and describedherein is similar to results achieved with a monochromator and greatlyexceed the results achieved through the Macbeth and MacbethDC reflectivepatches wherein the respective curves are not constant and haverelatively rapidly decreasing slopes. The accuracy of the calibrationmethods depends on how spectrally correlated the reflective patches orthe light emitting devices are to each other. More correlated patches orlight emitting devices produce less accurate calibrations. This is thecase because calibration techniques invert an image formation equationto compute the camera responsivity functions. When spectrally correlatedpatches or light emitting devices are inverted, noisy estimates of thecamera responsivity functions result. The singular values of thereflectance functions of patches or the spectral power distributions oflight emitting devices indicate the accuracy of a given method. The moresingular values which are greater than 0.01 (anything less may beconsidered too noisy), the more accurate the method (see e.g., FIG. 10).Basically, the number of singular values indicates the number of patchcolors or light emitting devices that contribute to the resultingcalibration.

Further, with respect to FIGS. 11-13, exemplary relative responsivitiesdetermined using Macbeth reflective patches (FIG. 11), MacbethDCreflective patches (FIG. 12) and the exemplary emissive calibrationinstrument 12 of FIG. 2 (FIG. 13) for a D1 digital camera available fromNikon are individually shown with respect to graphs measured using amonochromator. It is clear from a comparison of FIGS. 11-13 that thecalibration instrument 12 of FIG. 2 provides increased accuracy ofdetermining relative responsivities of a given imaging device 14compared with usage of reflective patches (e.g., Macbeth and MacbethDC).

Table 1 compares the calibration procedures using reflective charts, thecalibration instrument 12 of FIG. 2 and a monochromator. The calibrationinstrument 12 of FIG. 2 provides the shortest calibration time for agiven imaging device 14 (i.e., slightly shorter than the reflectivechart) and no uniformity of an external light source is required as withthe reflective chart, and hours shorter than a monochromator (i.e.,colors may be measured spatially in the configuration of FIG. 2 insteadof temporally as with the monochromator). Calibration instrument 12 hasthe shortest calibration time of the compared devices since externalsources of light do not have to be made uniform (e.g., the exemplaryinstrument 12 emits desired light itself).

TABLE 1 Reflective chart Calibration Instrument Monochromator 1.Uniformly illuminate the 1. Turn on the device. 1. Set monochromator toa    chart using an ambient 2. Take a photograph of the    specifiedwavelength and    source.    device.    bandwidth. 2. Take a photographof the 3. Run software to calibrate 2. Take a photograph of the    chart   light exiting the 3. Run software to calibrate.    monochromator. 3.Measure the power level of    the light exiting the    monochromator. 4.Repeat steps 1–3 for each    wavelength of the visible    spectrum. 5.Run software to calibrate.

Table 2 compares approximate cost of devices configured to implement theabove-described three calibration methods.

TABLE 2 Reflective chart Calibration Instrument Monochromator $50–$350(retail) $200–$400 (est. retail) $5,000–$20,000 (retail)

Table 3 compares the number of singular values of the three methods anddevices including the calibration instrument of FIG. 12. Otherembodiments of calibration instrument 12 may include more or lesswavelengths and/or intensities of light as desired. For example,embodiments of instrument 12 described above include twenty types ofdifferent light. In other embodiments, any appropriate number ofdifferent types of light (wavelength and/or intensity) may be usedsequentially, in plural regions, or according to other appropriateschemes.

TABLE 3 Reflective chart Calibration Instrument Monochromatorapproximately 4 15–20 (depends on >50 number of emissive sources)

Reflective charts because they have broadband, highly-correlated patchcolors, only contribute approximately 4 measurements that can be usedfor calibration. This is typically not adequate for calibrations ofimaging devices 14 comprising cameras. The monochromator, on the otherhand, produces over 50 calibration measurements because it typicallyuses narrow-band sources. Hence, the monochromator produces calibrationresults of increased accuracy, but the calibration time is relativelylong and the cost is relatively expensive. The exemplary calibrationinstrument 12 of FIG. 2 has an associated 15-20 measurements, forexample, which produces more than adequate calibration results fortypical imaging devices 14 (e.g., digital cameras), but it does notsuffer the cost and long calibration times of the monochromator orutilize external illumination as used with reflective patches.

Accordingly, at least some aspects of the disclosure allow for quick,accurate, and relatively inexpensive determination and calibrations ofresponsivity and transduction functions of imaging devices 14 and may beutilized to calibrate imaging devices on the manufacturing line in atleast one implementation. As discussed above, imaging devices 14 of thesame model or using the same type of components may have differentresponsivity and transduction functions due to sensor and/or colorfilter manufacturing variations. Calibration instruments 12 describedherein may be used for determining optical characteristics of thedevices 14 and calibrating the devices 14 before the imaging devices 14are shipped to a customer or dealer. The relatively quick and accuratecalibrations may improve the overall color reproduction quality ofindividually calibrated imaging devices 14.

Calibration instruments 12 or methods discussed herein may also be usedby professional or prosumer photographers for calibration of high-endimaging devices 14. It is believed that such calibrations would improvethe overall color reproduction quality of the resulting images generatedby such calibrated imaging devices 14. At least some such calibrationaspects may be focused to a more professional market inasmuch as somecalibration aspects utilize raw image data from the imaging device 14and typically, raw image data is provided by imaging devices 14developed for these markets.

At least some aspects described below disclose exemplary analysisoperations of an imaging device. Some of the described embodimentspermit testing and measurement of optical and electronic characteristicsof an imaging device in order to check quality control, assembly, andsoftware or firmware programming, and/or to measure and tune a device inthe field. For example, in addition to the above described analysisoperations, additional analysis may be performed with respect to focusoperations of the imaging device, filtering of an infrared cutofffilter, chromatic aberrations, pin cushion and barrel distortion,exposure speed, and determination of gain maps in exemplary embodiments.In some embodiments, analysis systems described herein may be used byimaging device testers with access to manual controls (e.g., in aninteractive mode), may implement analysis in an automated fashion (e.g.,self-service kiosk), or at a fabrication facility to verify operation ofimaging devices being manufactured. Analysis operations may be performedto test programming of an imaging pipeline of an imaging device byexposure of the imaging device to known color values which may betracked through the pipeline for debugging or other purposes. At leastsome embodiments are described with respect to stand-aloneimplementations for interfacing with imaging devices. In otherembodiments, the analysis systems or methods may be implementedinternally of a device such as a printer, computer, copier, etc.

Referring to FIG. 14, another embodiment of an imaging system 100 isillustrated. The imaging system 100 includes an imaging device analysissystem 112 and an imaging device 114. In one embodiment, imaging system100 may be configured similarly to the above-described imaging system10. For example, in some embodiments, analysis system 112 may beconfigured the same as or similar to calibration instrument 12 andimaging device 114 may be configured the same as or similar to imagingdevice 14, and for example, may comprise a camera, digital camera, videorecorder, scanner, copier, multiple function peripheral or otherconfiguration capable of capturing images and generating images. In someembodiments, imaging device 114 may comprise a color device capable ofcapturing color information of images and/or generating digital dataindicative of the captured color images.

The illustrated analysis system 112 includes an analysis device 120 anda computer 122 in one embodiment. In some embodiments, analysis device120 is configured to emit light 116 which may be captured by imagingdevice 114 in the form of digital information or on a substrate, such asfilm. Light 116 may be emitted within a housing 121 configured to reducethe presence of ambient light not emitted from the analysis device 120.Imaging device 114 may be optically coupled with an interior of thehousing 121 to receive the emitted light 116. In one embodiment,analysis system 112 and imaging device 114 are provided in a temperaturecontrolled facility to reduce effects of temperature upon analysisoperations. In one example, an HVAC system may be used to maintain aninterior of housing 121 and/or an environment about housing 121 at asubstantially constant temperature. In some arrangements, imaging device114 may be positioned within housing 121 during analysis.

Analysis device 120 and/or computer 122 (e.g., implemented as a personalcomputer) may be individually configured using at least some of thecircuitry as described with respect to FIG. 3 in one embodiment. Morespecifically, analysis device 120 and/or computer 122 may individuallycomprise a communications interface, processing circuitry, storagecircuitry, a light source, and/or a light sensor configured similar tosuch above-described components of FIG. 3 in one embodiment. Additionaldetails of exemplary embodiments are described herein and a co-pendingU.S. patent application entitled “Imaging Device Analysis Systems AndImaging Device Analysis Methods”, listing Steven W. Trovinger, Glen EricMontgomery, and Jeffrey M. DiCarlo as inventors, having Ser. No.11/054,209; and a co-pending U.S. application entitled “Imaging DeviceAnalysis Methods, Imaging Device Analysis Systems, And Articles OfManufacture”, listing Jeffrey M. DiCarlo and Casey Miller as inventors,having Ser. No. 11/054,193, and the teachings of both applications areincorporated herein by reference.

For example, still referring to FIG. 14, analysis device 120 mayadditionally include one or more mask 150, a motor 152, an emissionassembly 157 and bellows 158. In addition, analysis device 120 and/orcomputer 122 may individually comprise more or less components orcircuitry or alternative configurations (e.g., light source 154described herein).

In addition, imaging device 114 may be configured similar to theembodiment of FIG. 4 in one implementation and may include processingcircuitry, a strobe, optics (e.g., lens), a filter, an image sensor,and/or a communications interface configured similar to suchabove-described imaging components. Other embodiments of imaging device114 are possible and may include more or less components or circuitry.

Other embodiments of analysis system 100 are possible. For example,computer 122 may be omitted in some arrangements, and if appropriate,analysis device 120 and/or imaging device 114 may implementfunctionality otherwise provided by computer 122. More specifically, ifpresent, computer 122 may provide a user interface including a displayfor depicting information for a user and an input device configured toreceive input from a user. Computer 122 may additionally implementand/or control operations of analysis device 120 and/or imaging device114 to enable analysis of the imaging device 114. For example,processing circuitry of computer 122 may control light emissions ofanalysis device 120 and image capture operations of imaging device 114to capture images of the emitted light. For example, in one embodiment,computer 122 is configured to initiate analysis operations of imagingdevice 114 and may synchronize light emission operations of analysisdevice 120 with image capture operations or other operations of imagingdevice 114. In one embodiment, the appropriate processing circuitry mayautomatically control and implement the analysis operations (e.g.,without input from a user).

Processing circuitry of computer 122 may communicate information toand/or receive communications from analysis device 120 and/or imagingdevice 114. Processing circuitry may process received data, control theuser interface to illustrate test results to a user, provide calibrationdata for use in imaging device 114, and implement other desired aspectsof the analysis system 100.

As mentioned above, the above-described functions of computer 122 may beimplemented using analysis device 120 and/or imaging device 114 inarrangements wherein computer 122 is omitted. In embodiments whereincomputer 122 is omitted, analysis device 120 and/or imaging device 114may individually directly communicate with and/or control the otherdevice, interface with a user and perform other desired functions andoperations to enable analysis operations.

Mask 150 may be selectively positioned intermediate light source 154 andthe imaging device 114 to implement analysis of imaging device 14. Inone embodiment, a plurality of masks 150 are provided to implementdifferent analysis operations with respect to imaging device 114. Masks150 control the emission of one or more light beams using light 116 fromlight source 154 to implement analysis operations. As described below,different masks 150 may be used which correspond to different emissionsof light from light source 154. In some analysis embodiments, no mask150 is utilized intermediate light source 154 and imaging device 114.Motor 152 may be used to selectively move one or more mask 150 withrespect to a position intermediate light source 154 and imaging device114 responsive to control from computer 122 in one embodiment.

Emission assembly 157 may comprise a diffuser configured to mix lightemitted by light source 154. For example, light source 154 may comprisea plurality of light emitting devices (e.g., light emitting diodes)which are configured to emit light 116. In some analysis operations,plural light emitting devices correspond to a common wavelength oflight. Emission assembly 157 may mix the light from the different lightemitting devices to remove frequency variations and provide the light toimaging device 114 of a substantially single wavelength without thewavelength variations at a moment in time. In other embodimentsdescribed herein, light emitting devices of light source 154 emit light116 of different wavelengths. In some embodiments, emission assembly 157may be moved out of an optical path of light 116 by a user, motor 152,or other means.

In accordance with some analysis aspects, it is desired to emit at leastsome of the light beams of the respective different wavelengths fromemission assembly 157 having substantially the same intensity forcommunication to imaging device 114. In addition, light source 154 mayemit light beams of different intensity. The light beams of differentwavelengths or intensities may be emitted simultaneously and/orsequentially corresponding to respective different analysis operationsto be performed.

In exemplary arrangements described below, it may be desired to emitlight using groups of light emitting devices located at differentspatial locations. In one embodiment, the light source 154 may have arectangular surface area and a plurality of light emitting devices ofthe same or different wavelengths may be positioned across substantiallyan entirety of the surface area. As described below, different ones orgroups of the light emitting devices including spatially spaced devicesor groups may be used for different analysis operations. In anotherembodiment, the light emitting devices may be moved to desired locationsto perform different analysis operations. In another embodiment, aplurality of different configurations of light sources 154 may be usedtailored to the respective analysis operations to be performed. Detailsregarding exemplary analysis operations are discussed below inaccordance with some embodiments.

It may be desired to minimize or prevent the entry of ambient light(i.e., light not emitted by analysis device 120) into imaging device 114during analysis operations. In one embodiment, an optical interface(e.g., output of emission assembly 157) may have a sufficient size(e.g., 2″ diameter) which is larger than a light receiving member (e.g.,light receiving surface of a lens) of imaging device 114. Accordingly,the optical interface may be configured to entirely cover a lens ofimaging device 114 being analyzed to reduce or minimize the entry ofambient light into the imaging device 114. The optical interface of theemission assembly 157 and the lens of imaging device 114 may be broughtinto contact with one another or otherwise closely optically coupledduring analysis according to one aspect. Bellows 158 may also beprovided about an optical coupling of analysis device 120 and imagingdevice 114 to reduce the entry of ambient light into imaging device 114.

According to exemplary analysis embodiments, light beams of the same ordifferent wavelengths and/or intensities may be emitted from opticalinterface. The light beams may be emitted simultaneously or at differentmoments in time. Imaging device 114 may be controlled corresponding tothe emission of light 116 to, for example, capture images, lock focuswithout image capture, or perform other operations for implementinganalysis operations. Other operational aspects of analysis system 112 orimaging device 114 are possible according to other analysis aspects.

Referring now to FIGS. 15-17, exemplary operations with respect toanalysis of infrared filtering by imaging device 114 are described. Theexemplary described aspects test for the presence and properinstallation of an infrared cutoff filter in one embodiment.

FIG. 15 illustrates an exemplary configuration of light source 154 toenable analysis of the infrared filtering of imaging device 114according to one embodiment. FIG. 15 illustrates a plurality of groups153 of light emitting devices 155 which may be provided by light source154. As mentioned above, in one embodiment, light emitting devices 155may cover substantially an entirety of the surface area of light source154 and the depicted groups 153 are merely shown to indicate which onesof the light emitting devices 155 are used to implement infrared cutofffilter analysis operations according to the described embodiment. Inanother embodiment, FIG. 15 represents the actual layout of the lightemitting devices 155 of the light source 154. Plural groupings 153 maybe used at different spatial locations as shown in the example to enableanalysis operations of imaging device 114 at different spatiallocations. No mask is utilized in the exemplary described infraredanalysis and other embodiments of light source 154 are possible toimplement the analysis.

Each of the groupings 153 may simultaneously emit light from respectivelight emitting devices 155 of different wavelengths and including lighthaving wavelengths below and above 700 nm in one operational embodiment.For example, progressing from left to right, the light emitting devices155 may emit light having wavelengths of 660 nm, 740 nm, 860 nm, 890 nm,935 nm, and 1030 nm in one implementation.

Referring to FIGS. 16A-16B, output of pixel locations of an image sensorcorresponding to one of the groupings 153 is shown. The output is shownfor plural light sensing devices (e.g., charge coupled devices) of animage sensor of imaging device 114 in one embodiment. The examples showresults of a properly functioning infrared cutoff filter of imagingdevice 114 (FIG. 16A) and a defective infrared cutoff filter (FIG. 16B).In particular, imaging device 114 may be controlled to capture lightemitted from the groupings 153 of light source 154. If the infraredcutoff filter is working properly as shown in FIG. 16A, the pixel valuesof respective sensing devices of the image sensor corresponding to theleftmost light emitting device 155 indicate the reception of the lightof 660 nm while the pixel values of the sensing devices corresponding tothe remaining light emitting devices 155 and wavelengths above 700 nmreflect little or no reception of light. If the infrared cutoff filteris not working properly as shown in FIG. 16B, the pixel values ofrespective sensing devices of the image sensor corresponding to lightemitting devices 155 of the respective group 153 indicate the receptionof all of the emitted light including infrared light. Appropriate actionmay be taken if the infrared cutoff filter is not working properly, forexample, by replacing the filter.

Referring to FIG. 17, an exemplary process is illustrated for analyzingthe operation of infrared filtering. Appropriate processing circuitry ofanalysis system 112 and/or imaging device 114 may control or implementat least some of the depicted steps in one embodiment. Other methods arepossible including more, less or alternative steps.

At a step S110, the light source is configured to emit light atpositions at least corresponding to the light emitting devices of FIG.15 and including light within and outside of the infrared spectrum.

At a step S112, the image sensor of the imaging device is controlled tocapture an image corresponding to the emitted light thereby producingimage data.

At a step S114, the image data of the image sensor may be processed. Inan exemplary embodiment wherein the positioning of the imaging device114 with respect to the light source 154 is controlled or known, therespective pixel locations of the image sensor corresponding tolocations of light emitting devices 155 are known and the image data maybe read directly for the appropriate pixel locations. If the pixellocations are not known, an algorithm may be executed to locate thepixels comprising the desired image data for each of the light emittingdevices 155 and generated responsive to the emitted light. An exemplarysearch algorithm is described in U.S. Pat. No. 5,371,690, the teachingsof which are incorporated herein by reference. Once the pixel locationsare identified, the image data may be accessed by the processingcircuitry. The processing circuitry may compare intensity information ofthe individual respective pixel locations resulting from light from eachof the light emitting devices 155 with respect to a threshold todetermine whether the infrared cutoff filter is working properly. Foreach of the light beams of devices 155, an average of image data fromadjacent pixels or peak values may be used for comparison inillustrative embodiments. The sensitivity of the light sensing devicesmay be different for different wavelengths of light. In exemplaryembodiments, the processing circuitry may use different thresholds fordata provided by pixel locations which received different wavelengths oflight or normalize the output of the light sensing devices forcomparison to a single threshold.

At a step S116, the results of the analysis may be outputted forcommunication to a user. For example, computer 122 may display graphssimilar to FIGS. 16A-16B and/or provide a pass/fail indication of theinfrared filtering operations.

Referring now to FIGS. 18-22B, exemplary operations for analysis ofchromatic aberrations of imaging device 114 are described. In oneembodiment, chromatic aberration is measured across a field of view ofthe imaging device 114. FIG. 18 illustrates an exemplary configurationof light emitting devices 155 of light source 154 used to implement thedescribed analysis and FIG. 19 illustrates an exemplary configuration ofa mask 150 which corresponds to the devices 155 used in FIG. 18according to one embodiment. Computer 122 may control motor 152 to movemask 150 into an appropriate position intermediate light source 154 andemission assembly 157 when chromatic aberration analysis is to beperformed.

As shown in FIG. 18, groupings 153 a may be provided at differentspatial locations to enable analysis operations of imaging device 114using the different spatial locations. Individual ones of the groupings153 a include light emitting devices 155 configured to emit light ofdifferent wavelengths (e.g., blue 400-450 nm, green 500 nm, and red650-700 nm in one embodiment).

Two dimensions (i.e., width and height) of mask 150 are shown in FIG. 19and define an area. The area corresponds to an area of light emittingdevices of light source 154 in one embodiment. For example, as mentionedabove, light source 154 may include a plurality of light emittingdevices 155 across an area (e.g., which may correspond to the areasshown in FIGS. 18-19 although only devices 155 of the groupings 153 aare shown in FIG. 18). Mask 150 includes a plurality of apertures 160corresponding to respective groupings 153 a of light emitting devices155. Apertures 160 may comprise pinholes configured to pass lightcorresponding to light emitting devices 155 aligned with and locatedbehind apertures 160. Groupings 153 a are arranged in one embodimentsuch that the light from the individual devices 155 is mixed when viewedthrough mask 150. Other arrangements could include LEDs with multiplediodes in the same package, usage of a diffuser with mask 150, and/orother mixing implementations.

Referring to FIG. 20, an exemplary process is illustrated for attemptingto detect chromatic aberrations of imaging device 114. Appropriateprocessing circuitry of analysis system 112 and/or imaging device 114may control or implement at least some of the depicted steps in oneembodiment. Other methods are possible including more, less oralternative steps.

At a step S120, appropriate light emitting devices 155 of the groupings153 a are configured to emit light. In the described exemplaryembodiment, only the intermediate wavelength (e.g., green) lightemitting devices 155 emit light beams at step S120.

At a step S122, the imaging device 114 receives the light beams andlocks focus during the emission of the light in step S120.

At a step S124, the long and short wavelength light emitting devices 155(e.g., red and blue) are simultaneously controlled to emit light whichis passed through respective apertures 160 of mask 150. The light fromthe light emitting devices 155 may be mixed to provide light beams of adifferent wavelength than the wavelength of the light beams emitted instep S120. For example, mixing may be provided using a diffuser ofemission assembly 157 and/or a diffuser (not shown) prior to passage oflight through apertures 160 in possible embodiments.

At a step S126, the imaging device 114 is controlled to capture an imageof the light beams emitted at step S124 at the focus determined in stepS122. The captured image may be underexposed or the imaging device 114may be otherwise controlled to capture the image at a desired exposuresetting in exemplary embodiments. Controlling the exposure in someembodiments may avoid or reduce “blooming” or other enlargements due toexcessive exposure to increase the accuracy of the analyses.

At a step S128, image data of the captured image is processed. Referringto FIGS. 21A and 21B, exemplary pixel locations 147 of an image sensor146 which received image data in possible scenarios are shown. FIG. 21Aillustrates an example wherein no or minimal chromatic aberrations arepresent within imaging device 114. FIG. 21B illustrates an examplewherein chromatic aberrations are present. The pixel locations 147 ofFIG. 21A which received emitted light (e.g., purple in the describedexample) are more focused compared with FIG. 21B. The pixel locations147 of FIG. 21B illustrate pixels 148 which received purple light in thedescribed example and surrounding pixels 149 which received blue lightin the described example. FIG. 22A illustrates another representation ofthe results of FIG. 21A showing a comparatively focused group of pixellocations which received purple light 170. FIG. 22B illustrates anotherrepresentation of the results of FIG. 21B showing the focused group ofpixel locations which received purple light 170 as well as a relativelylarge number of pixel locations which received at least some blue light172. The presence of pixels 149 shown in FIG. 21B receiving light isindicative of a chromatic aberration in imaging device 114. In oneembodiment, appropriate processing circuitry may search the pixellocations of the image sensor 146 to identify the areas of the pixellocations 147 which received light. Once determined, the processingcircuitry may compare the areas or number of the light sensing devicesfor the pixel locations 147 which received light corresponding to eachof the light beams emitted from groupings 153 a. If one or more of theareas is greater than a threshold, then a chromatic aberration ispresent in one embodiment. The threshold may be determined based uponthe desired accuracy of the imaging device 114. In another embodiment, acolor sensitive sharpness detection algorithm may be executed upon theimage data to distinguish between the results of FIGS. 21A and 21B todetermine whether a chromatic aberration is present. Other processingembodiments are possible.

At a step S130, the results of the analysis may be outputted forcommunication to a user. For example, computer 122 may displayillustrations similar to FIG. 21A-21B or 22A-22B and/or provide apass/fail indication.

Referring now to FIGS. 23-26, exemplary operations with respect toanalysis of the ability of imaging device 114 to correctly focus imagesare described. The operations may analyze a focus mechanism and/oralgorithm of the imaging device 114 in some implementations.

FIG. 23 illustrates an exemplary arrangement of a plurality of spatiallyseparated light emitting devices 155 of light source 154 arranged in agrid pattern which may be illuminated to test focus operations ofimaging device 114 in one embodiment. In the depicted embodiment, thelight emitting devices 155 which emit light are spatially separatedalong two dimensions (e.g., x and y dimensions of a rectangulararrangement in the described embodiment) within a field of view ofimaging device 114. Light of any suitable wavelength may be emitted inone embodiment. Mask 150 a of FIG. 24 may be moved into appropriateposition intermediate light source 154 and emission assembly 157 whenfocus operations are analyzed. Mask 150 a includes a plurality of pinhole apertures 160 which correspond to the illuminated devices 155 ofFIG. 23.

Imaging device 114 is controlled to capture the light simultaneouslyemitted by the light emitting devices 155 through apertures 160 of mask150 a. Referring to FIGS. 25A-25B, output of pixel locationscorresponding to plural light sensing devices of the image sensor whichreceived one of the light beams from the devices 155 of FIG. 23 is shownfor proper focusing operations of imaging device 114 (FIG. 25A)indicating the ability of the imaging device 114 to focus and processthe received light and defective focusing operations (FIG. 25B) whereinthe light of one of the light beams emitted from light source 154 isblurry when received and processed by imaging device 114. Appropriateaction may be taken if the focus operations is not working properly, forexample, by replacing the focus mechanism. In the described embodiment,the pixel locations of the image sensor receiving the light beamsemitted by emitting devices 155 generally correspond to the spatialarrangement of the light emitting devices 155 and may be used to analyzethe focusing capabilities of imaging device 114 over a plurality ofspatial locations.

Referring to FIG. 26, an exemplary process is illustrated for analyzingthe focus operations of the imaging device 114. Appropriate processingcircuitry of analysis system 112 and/or imaging device 114 may controlor implement at least some of the depicted steps in one embodiment.Other methods are possible including more, less or alternative steps.

At a step S140, the appropriate light emitting devices 155 areconfigured to emit light.

At a step S142, the imaging device 114 is instructed to capture an imageof the received light. The captured image may be underexposed or theimaging device 114 may be otherwise controlled to capture the image at adesired exposure setting in exemplary embodiments.

At a step S144, the image data is processed to analyze the focusingoperations. Similar to the method of FIG. 20, the processing circuitrymay identify light sensing devices of the image sensor which receivedthe emitted light and determine the areas (or number) of light sensingdevices of the light sensor which received light from each of therespective light emitting devices 155. If the areas are individuallyless than a threshold, the focusing of the imaging device 114 may bedeemed acceptable in one embodiment. If one or more of the areas aregreater than a threshold, the focusing operations may be deemeddefective in one embodiment. In another embodiment, a sharpnessdetection algorithm may be utilized to analyze the results from theimage sensor.

At a step S146, the results of the analysis may be outputted forcommunication to a user. For example, computer 122 may displayillustrations similar to FIGS. 25A-25B and/or provide a pass/failindication to characterize the ability of the lens to focus and processreceived images.

Referring to FIGS. 27A-28, exemplary aspects are described with respectto analyzing optics of the imaging device 114 including identifying thepresence of pin cushion or barrel distortion according to exemplaryembodiments. In one embodiment, the operations with respect to thisanalysis may be performed after the above-described operations withrespect to the focus test have been performed for the respective imagingdevice 114 and focus test results were acceptable.

The pattern of light emitting devices 155 which emitted light in FIG. 23and the mask 150 a of FIG. 24 may be utilized in one embodiment. Forexample, the light emitting devices 155 may be arranged in a patternincluding a plurality of straight lines comprising rows and columns of agrid. Other patterns of devices 155 are possible. Exemplary resultsdetermined by image data captured by the image sensor responsive to thereceived light are shown in FIG. 27A which is indicative of pin cushiondistortion in the optics and FIG. 27B which is indicative of barreldistortion in the optics (i.e., the number of depicted pixel locations147 which received light is greater than the number of light emittingdevices 155 of FIG. 23 which emitted light to facilitate the graphicalrepresentation of the pin cushion and barrel distortion). If nodistortion is present, the light sensing devices of the image sensorwhich received the light should resemble a grid similar to the array oflight emitting devices 155 which emitted the light through therespective apertures 160 as represented by exemplary straight lines 151corresponding to rows and columns. Once pixel locations 147 of lightsensing devices of the image sensor which received the light areidentified (e.g., using a search algorithm), the processing circuitryattempts to determine whether the pixel locations 147 occur within apattern aligned with or otherwise corresponding to the pattern of thelight emitting devices 155 which emitted the light beams. For example,the processing circuitry may determine if the light was received bylight sensing devices arranged in straight lines 151 of rows and columnsof the respective pattern within acceptable tolerance levels. Theprocessing circuitry may identify some of the pixel locations 147corresponding to rows and columns. A defective imaging device 114 may beidentified if one or more of the remaining pixel locations 147 deviatesfrom the determined rows or columns by a distance in excess of athreshold. In another embodiment, the pixel locations 147 may bedisplayed for observation by a user and a user may determine whether theimaging device 114 passed or failed the test analysis. Other processesmay be used to identify the distortion and/or determine whether theresults are acceptable or not.

Referring to FIG. 28, an exemplary process is illustrated for analyzingfor the presence of pin cushion or barrel distortion of the imagingdevice 114. Appropriate processing circuitry of analysis system 112and/or imaging device 114 may control or implement at least some of thedepicted steps in one embodiment. Other methods are possible includingmore, less or alternative steps.

At a step S150, the appropriate light emitting devices 154 arranged in agrid (e.g., FIG. 23) in one embodiment are configured to emit light.

At a step S152, the imaging device 114 captures an image of the receivedlight. The captured image may be underexposed or the imaging device 114may be otherwise controlled to capture the image at a desired exposuresetting in exemplary embodiments.

At a step S154, the image data is processed to determine the presence ofabsence of distortion. The processing circuitry may identify pixellocations of light sensing devices of the image sensor which receivedthe emitted light and attempt to map the pixel locations to rows andcolumns of a grid. A pass status may be indicated if the mapping isprovided within an acceptable tolerance, otherwise the imaging device114 may be indicated to be defective.

At a step S156, results of the analysis may be outputted forcommunication to a user. For example, computer 122 may displayillustrations similar to FIGS. 27A-27B and/or provide a pass/failindication.

Referring to FIGS. 29-31, exemplary aspects are described with respectto analyzing exposure operations (e.g., shutter and/or image sensorexposure speed) of the imaging device 114 according to one embodiment.

Referring to FIG. 29, exemplary light emitting devices 155 of lightsource 154 which emit light are shown according to the describedembodiment. According to one embodiment, a plurality of light beams areilluminated at known times for known durations to test shutter (ifpresent) and image capture or exposure time of an image sensor ofimaging device 114. First and second groupings 153 b, 153 c are showncomprising plural light emitting devices 155 spatially separated fromone another in the example FIG. 29. The light emitting devices 155 offirst grouping 153 b are provided as a control or reference to assistwith the analysis operations and may be constantly illuminated duringanalysis procedures. A second grouping 153 c of light emitting devices155 is arranged to implement operations to test shutter speed operationsof imaging device 114. In the depicted embodiment, the leftmost andrightmost light emitting devices 155 of second grouping 153 c may becontrol or reference devices and constantly illuminated during theanalysis procedures. The control light emitting devices 155 are shown asreference 180 in the example of FIG. 29. The light emitting devices 155intermediate the control devices 180 of the second grouping 153 c may bereferred to as analysis devices 182 in the described embodiment.

To analyze the exposure speed operations, the imaging device 114 isinstructed to capture an image at a desired exposure speed as theanalysis devices 182 are sequentially illuminated. In the describedembodiment, individual ones of the analysis devices 182 are illuminatedfor a common duration less than the exposure time of imaging device 114(e.g., when a shutter of the imaging device 114 is open and/or thelength of time of exposure of the image sensor) corresponding to aselected exposure speed (e.g., an exemplary illumination duration of1/1000 second for analysis devices 182 may be used for an exposure speedof 1/125 second). The number of analysis devices 182 from which lightwas captured by the imaging device 114 during the exposure is indicativeof the exposure speed in one embodiment.

More specifically, referring to FIG. 30, test results of an exposurespeed setting of 1/125 for a properly functioning imaging device 114 isshown. As shown in FIG. 30, a plurality of pixel locations 147 of theimage sensor which received light are shown. Light from the controldevices 180 is shown at pixel locations 184 while light from eight ofthe analysis devices 182 is shown at pixel locations 186. Light fromeight of the analysis devices 182 indicates that the exposure operationwas acceptable in the described exemplary embodiment (i.e., eight times1/1000= 1/125). Light at more or less pixel locations 186 indicates thatthe exposure speed is slow or fast, respectively. The duration ofillumination of individual ones of the analysis devices 182 may bevaried in other embodiments to test other exposure speeds.

Referring to FIG. 31, an exemplary process for analyzing the shutterspeed of imaging device 114 is illustrated. Appropriate processingcircuitry of analysis system 112 and/or imaging device 114 may controlor implement at least some of the depicted steps in one embodiment.Other methods are possible including more, less or alternative steps.

At a step S160, the appropriate light emitting devices 154 arecontrolled to emit light. The emission includes constantly illuminatingthe control devices 180 and sequentially illuminating the analysisdevices 182 for a desired duration in one embodiment.

At a step S162, the imaging device 114 captures an image of the receivedlight according to a desired shutter speed setting. The captured imagemay be underexposed or the imaging device 114 may be otherwisecontrolled to capture the image at a desired exposure setting inexemplary embodiments.

At a step S164, the image data from a light sensor of the imaging device114 is processed to implement analysis operations with respect to thespeed of the shutter. The processing circuitry may add the number ofpixel locations 186 which received light and multiply the result by theduration of illumination of individual ones of the analysis devices 182to provide information regarding the shutter speed operations.

At a step S166, results of the analysis may be outputted forcommunication to a user. For example, computer 122 may display anillustration similar to FIG. 30, provide the calculated shutter speedand/or provide a pass/fail indication.

Referring to FIG. 32, exemplary aspects are described for calculatinggain maps of a respective imaging device 114 according to oneembodiment. The gain maps may provide a calibration/compensation foruneven luminance response across the image sensor of the respectiveimaging device 114. The gain maps may be calculated and stored in therespective imaging device 114 and applied to subsequently generatedimage data to reduce effects of image sensor variances of differentimaging devices 114 and/or lens fall off of the respective imagingdevice 114 if device 114 includes a lens. Appropriate processingcircuitry of analysis system 112 and/or imaging device 114 may controlor implement at least some of the depicted steps in one embodiment.Other methods are possible including more, less or alternative steps.

At a step S170, the light source 154 is controlled to emit light foranalysis operations. In one embodiment, a sufficient number of lightemitting devices 155 of the light source are controlled to providesubstantially uniform illumination by light source 154. The emittedlight is substantially neutral (white) in one embodiment. The light maybe mixed using a diffuser such as emission assembly 157.

At a step S172, the imaging device 114 is controlled to capture an imageof the emitted light. A plurality of color channels (e.g., red, greenand blue) may be measured separately from the image sensor responsive tothe emitted light.

At a step S174, image data from the image sensor of the imaging device114 is accessed. A plurality of sections may be defined for the imagesensor and the image data. Individual sections may be as small as asingle pixel location or larger. For example, if the image sensor isembodied as a rectangle, a plurality of sections may be definedaccording to a grid including seven sections in the x direction and fivesections in the y direction in but one embodiment. The sections may beuniformly sized to comprise the same number of pixel locations in oneembodiment.

For individual ones of the sections, average pixel values are calculatedfor respective ones of the color channels and the determined averagepixel values for the section are summed in one embodiment. The sectionhaving the largest summed value is identified (e.g., typically thesection located at the center of the image sensor). Following theidentification, a plurality of correction factors may be identified forthe other sections usable to bring the average values of the sections toequal the determined highest value. For example, for a given section n,the respective correction factor for a given channel (e.g., red) may becalculated as follows:Red Correction Factor_(n)=Red Highest Average/Red Section_(n) AverageCorrection factors may be similarly determined for the other colorchannels of the respective section. Thereafter, additional correctionfactors for the channels may be calculated for the remaining sections.The correction factors determined in accordance with the above exemplaryequation are ratios indicative of a relationship of intensities of imagedata of pixels of the respective sections.

At a step S176, the calculated correction factors are stored as a gainmap for the respective imaging device 114 and subsequently applied toimage data acquired by the image sensor of the imaging device. Forexample, the appropriate correction factors may be multiplied by dataacquired by respective sections of the light sensor of the imagingdevice 114. In one embodiment, the gain maps are stored using storagecircuitry of the respective imaging device 114.

The above-described exemplary method provides a one-point correction(e.g., a uniform white correction factor in the described embodiment).In other embodiments, other corrections may be provided (e.g., athree-point correction for increased accuracy). In one three-pointimplementation, the light is emitted from light source 154 at differentintensities of the light emitting devices 155 (e.g., full intensity, 50%intensity for 50% uniform gray, and 20% intensity for 20% uniform gray).Thereafter, a plurality of correction factors may be determined for anindividual channel of an individual section for the differentintensities. The correction factors for full intensity may be determinedusing the formula described above with respect to step S174 in oneembodiment. The correction factors for the 50% and 20% intensities maybe calculated using plural different emissions of light at 50% and 20%intensities and the same formula but substituting fixed values for thenumerator of the formula (e.g., for eight bit output at respective pixellocations a value of 128 may be used for the 50% uniform gray and avalue of 51 may be used for 20% uniform gray).

Thereafter, one of the three correction factors of a respective channelof a respective section may be selected according to the value of therespective image data for the channel. For example, if an eight bitvalue provided by a pixel location is between an intensity range of0-80, the 20% intensity correction factor may be used. If the value isin the intensity range of 81-191, the 50% intensity correction factormay be used. If the value is in the intensity range of 192-256, theuniform white correction factor may be used. After the respectivecorrection factor is identified, the image data for the pixel locationmay be modified using the respective correction factor. In otherembodiments, more or less correction factors may be calculated and used.

Exemplary aspects of at least one embodiment enable numerous differentanalysis operations of an imaging device to be performed by the analysissystem (e.g., measure, calibrate, tune and/or upgrade imaging devices).Advantages of some embodiments include reduced cost for providing theanalysis operations in less time facilitating usage in high volumeapplications such as in a fabrication environment. In one embodiment,the analysis operations are automated using minimal or no input from auser. Accordingly, novice users may interact with disclosed systems anddevices to implement analysis of their imaging device. Using theapparatus and methods described herein, analyzed imaging devices may betuned to deliver improved image quality and/or other features. Theexemplary described analysis aspects may be performed at a time ofmanufacture of the imaging device as well as after sale of the imagingdevice inasmuch as an image sensor of the imaging device may changecharacteristics over time resulting in degraded image quality.

The protection sought is not to be limited to the disclosed embodiments,which are given by way of example only, but instead is to be limitedonly by the scope of the appended claims.

What is claimed is:
 1. An imaging device analysis system comprising: alight source that outputs light for use in analyzing at least oneimaging component comprising a lens of an imaging device that generatesimages responsive to received light, wherein the light source outputsfirst light having a first wavelength characteristic at a first momentin time and outputs second light having a second wavelengthcharacteristic different from the first wavelength characteristic at asecond moment in time, and the light source outputs the second light asa plurality of light beams directed along different respective spatiallyseparated beam paths; and processing circuitry that is coupled with thelight source and controls the light source to optically communicate thelight to the imaging device and to lock a focus of the lens of theimaging device using the light of the first wavelength characteristic atthe first moment in time, wherein the processing circuitry accessesimage data generated by the imaging device in response to receipt of thelight from the light source having the second wavelength characteristicat the second moment in time with the focus of the lens locked, theprocessing circuitry identifies in the image data areas corresponding tolocations of an image sensor of the imaging device that received lightof second wavelength characteristic, and the processing circuitrydetermines whether a chromatic aberration is present within the lensbased on an analysis of the identified areas.
 2. The system of claim 1wherein the light source is configured to output the light comprisinginfrared light for use in testing at least one imaging componentcomprising the lens and an infrared cutoff filter configured to filterinfrared light.
 3. The system of claim 1 further comprising a mask thatcomprises a plurality of spatially separated apertures in aconfiguration matching a spatial arrangement of the plurality of lightbeams output by the light source, the mask being selectively moveable toa position intermediate the light source and the imaging device.
 4. Thesystem of claim 3 wherein the processing circuitry is configured tocontrol movement of the mask with respect to the position.
 5. The systemof claim 1, wherein the processing circuitry is configured to processthe image data generated at a plurality of pixel locations of the imagesensor of the imaging device corresponding to the identified areas inthe image data to determine the operational status comprising distortionof the at least one imaging component comprising the lens of the imagingdevice.
 6. The system of claim 1 wherein individual ones of the lightbeams are outputted for a duration less than an exposure time of theimaging device, and the processing circuitry is configured to processthe image data to determine the operational status comprising shutterspeed of the at least one imaging component comprising a shutter of theimaging device.
 7. The system of claim 1 wherein the processingcircuitry is configured to determine the operational status of the atleast one component comprising an image sensor, and to determine atleast one correction factor for use in modification of image datagenerated using the image sensor.
 8. The system of claim 1 wherein theprocessing circuitry is configured to process the image data comprisingcomparing a number of pixels of the image sensor which received thelight having the second wavelength with respect to a threshold todetermine whether the chromatic aberration is present.
 9. An imagingdevice analysis method comprising: fixing focus of a lens of an imagingdevice configured to generate images responsive to received light;outputting a plurality of light beams directed along differentrespective spatially separated beam paths, wherein each light beamcomprises light in each of multiple discrete wavelength ranges;receiving the light beams using the imaging device after the fixing;generating image data using the imaging device responsive to thereceiving the light beam; identifying in the image data areascorresponding to locations of an image sensor of the imaging device thatreceived the light beams; and determining whether a chromatic aberrationof the lens of the imaging device is present based on an analysis of theidentified areas, wherein for each of the identified areas of theimaging device the analysis comprises ascertaining different regions ofthe identified area that received light having different respectivemixes of the discrete wavelength ranges of light.
 10. The method ofclaim 9 wherein: the fixing comprises outputting first light having afirst wavelength characteristic and locking a focus of the lens of theimaging device using the light of the first wavelength characteristic;and the outputting comprises outputting the plurality of light beamswith a second wavelength characteristic different from the firstwavelength characteristic.
 11. The method of claim 9 further comprising:providing a mask comprising a plurality of apertures; passing the lightbeams through respective ones of the apertures; and wherein thereceiving comprises receiving after the passing.
 12. The method of claim9 wherein the receiving the light beams comprises receiving using animage sensor of the imaging device, and wherein the determiningcomprises: identifying a number of pixel locations of the image sensorwhich received the light beams; and comparing the number of pixellocations with respect to a threshold.
 13. The method of claim 12wherein the analyzing identifies that the chromatic aberration of thelens is present if the comparing determines that the number of pixellocations which received the light beam exceeds the threshold.
 14. Themethod of claim 9 wherein the outputting the light beams comprisesoutputting light of a plurality of wavelengths and mixing the light ofthe plurality of wavelengths.
 15. The method of claim 9 wherein thegenerating comprises generating using the imaging device with the focusof the lens of the imaging device the same as during the fixing.
 16. Themethod of claim 9 wherein the fixing comprises fixing prior to thereceiving, and the receiving and the generating comprise receiving andgenerating using the imaging device with the focus of the lens of theimaging device the same as during the fixing.
 17. An imaging deviceanalysis method comprising: outputting a light beam for communication toan imaging device configured to generate images responsive to receivedlight; focusing the light beam using a lens of the imaging device; afterthe focusing, receiving the light beam using an image sensor of theimaging device; generating image data using the image sensor of theimaging device responsive to the receiving the light beam; processingthe image data corresponding to a plurality of pixel locations of theimage sensor, wherein the processing comprises determining respectivesizes of one or more areas of the image sensor illuminated by the lightbeam and ascertaining whether a chromatic aberration is present based onthe one or more determined sizes; and indicating results of the focusingby the lens using the processing.
 18. The method of claim 17 wherein theoutputting comprises outputting a plurality of light beams spatiallyseparated from one another, and wherein the processing comprisesprocessing the image data at the pixel locations spatially separatedfrom one another and corresponding to spatial locations of the lightbeams.
 19. The method of claim 17 wherein the light beams are spatiallyseparated from others of the light beams along two dimensions within afield of view of the lens of the imaging device.
 20. The method of claim17 wherein the outputting comprises outputting a plurality of lightbeams and passing the light beams through a mask.
 21. The method ofclaim 17 wherein the determining comprises identifying a number of pixellocations which received light of the light beam and the ascertainingcomprises comparing the number of pixel locations with respect to athreshold.
 22. The method of claim 21 wherein the indicating comprisesindicating that the ability of the lens to focus is unacceptable if thenumber of pixel locations which received the light beam exceeds thethreshold.
 23. The method of claim 17 wherein the indicating comprisesindicating the results of the focusing by the lens comprisinginformation regarding an ability of the lens to focus the light beam.24. The method of claim 17 wherein the indicating comprises indicatingthe results of the focusing by the lens comprising information regardingaccuracy of the focusing of the light beam using the lens of the imagingdevice.
 25. An imaging device analysis method comprising: outputting aplurality of light beams for communication to an imaging deviceconfigured to generate images responsive to received light, wherein theoutputting comprises outputting the plurality of light beams in apattern that provides the light beams arranged in a plurality ofstraight lines; accessing image data generated by the imaging deviceresponsive to the light beams communicated to the imaging device;processing the image data to identify in the image data areascorresponding to locations of an image sensor of the imaging device thatreceived the light beams, wherein the processing comprises identifying aplurality of pixel locations of the imaging device which received thelight beams, comparing the pixel locations to the pattern, and analyzingalignment of the pixel locations with respect to the straight lines; anddetermining distortion of optics of the imaging device based on theanalyzing of the identified areas.
 26. The method of claim 25 whereinthe pattern comprises the light beams arranged in a plurality ofstraight lines comprising rows and columns of a grid.
 27. The method ofclaim 25 wherein the providing information comprises providinginformation regarding pin cushion distortion.
 28. The method of claim 25wherein the providing information comprises providing informationregarding barrel distortion.
 29. The method of claim 25 wherein theproviding the information regarding distortion comprises indicatingwhether the lens has an acceptable amount of distortion or unacceptableamount of distortion.
 30. The method of claim 25 wherein the providingthe information regarding distortion comprises providing using theprocessing of the image data which is indicative of intensity of thelight beams received by a plurality of pixels of the imaging device. 31.The method of claim 25 wherein the providing information comprisesproviding the information to indicate that the optics of the imagingdevice have unacceptable distortion as a result of the comparing. 32.The method of claim 31 wherein the providing information to indicatethat the optics of the imaging device have unacceptable distortioncomprises providing as a result of the comparing determining that adeviation of at least one of the pixel locations from the patternexceeds a threshold.
 33. The method of claim 25, wherein the pluralityof light beams are outputted in a pattern that provides the light beamsin a rectangular grid pattern of spaced-apart beam locations.